The invention relates generally to surface mounted connectors on printed circuit boards, and more specifically, to a high density flexible contact system for use in socket connectors.
The trend toward smaller, lighter, and higher performance electrical components and higher density electrical circuits led to the development of surface mount technology in the design of printed circuit boards. As is well understood in the art, surface mountable packaging allows for the connection of an electronic package to pads on the surface of the circuit board rather than by contacts or pins soldered in plated holes going through the circuit board. Surface mount technology allows for an increased component density on a circuit board, thereby saving space on the circuit board.
The land grid array (LGA) is one type of surface mount electronic package that has developed in response to the demand created by higher density electrical circuits for increased density of electrical connections on the circuit board. The land grid array includes an array of connections on the bottom side of the package. In the traditional land grid array connector, stamped and formed contacts having flexible contact beams are soldered to the circuit board using solder halls placed at contact locations on the circuit board. The contact beams must be compressed or deflected sufficiently to generate a required normal force on the package to reliably mate the package to the contacts. As a result, the stamped and formed contacts must have sufficient length and working range to generate the required normal force. In some socket connectors, stamped and formed contacts are replaced with compressible conductive polymer columns. However, as contact size decreases and as contact density increases, such devices may encounter problems associated with creep of the polymer material with time and at elevated temperatures. Next generation devices such as mobile and desktop devices may be expected to require even more reduction in contact pitch in interconnect devices, due to size and space limitations while providing improved electrical performance.
Thus, a need exists for a compressible contact system that can be economically produced at a reduced contact pitch to meet the demands for improved electrical performance at higher contact densities.